WorkSafe's chief inspector Steve Kelly said the victim, a migrant worker with English as his second language, was not aware that standing on the drawbar of the trailer was a hazard.
The worker slipped from the drawbar and was drawn underneath the trailer and run over by the moving wheels.
"WorkSafe's investigation found it was common practice for calf collection workers to stand on the drawbar, but this absolutely should not have been allowed."
Kelly said at any farm where English might be a second language for workers, employers needed to take extra precautions to ensure workers met and understood health and safety responsibilities.